Q: What is centrifugal water pump efficiency? What is the formula?
A: The centrifugal water pump efficiency means the ratio between effective power and shaft power.η=Pe/P
Centrifugal water pump power usually means input power, that is too say the driven forwarded power to the pump shaft, so also call it shaft power. Use P to instead.
The efficient power means: pump head x weight flow rate x acceleration of gravity.